The invention relates to a cassette for holding a magnetic tape which can be guided inside the cassette along a side wall thereof which has an access opening through which at least one magnetic head can be brought into scanning contact with the magnetic tape by insertion of said magnetic head into the cassette. The cassette includes a pad-like pressure member adapted to press a magnetic tape against the inserted magnetic head, which pressure member is movable transversely of the side wall and is secured to a central portion of a substantially elongate blade-spring-like pressure-member support which is arranged to extend substantially parallel to the side wall with the access opening and has side portions situated adjacent the central portion. The cassette further includes two tape-guide elements adapted to guide a magnetic tape past the inserted magnetic head. The tape-guide elements are movable substantially transversely of the side wall and are arranged substantially mirror-symmetrically relative to the pressure member on a substantially elongate blade-spring-like tape-guide-element support which is arranged to extend substantially parallel to the side wall and substantially between the pressure-member support and the side wall. The tape-guide-element support has side portions which are also situated adjacent its central portion, and two abutment parts which are arranged in the area of the side portions of the pressure-member support and the tape-guide-element support at their sides which are remote from the side wall, and which, with a magnetic head inserted, take up the forces exerted by the side portions of the pressure-member support and the tape-guide-element support.
The invention also relates to a pressure-member support for a cassette as defined in the first paragraph, which support is of a substantially elongate and blade-spring-like construction and comprises a central portion for securing a pressure member and, situated adjacent the central portion, two side portions adapted to cooperate with abutment parts of the cassette.
The invention further relates to a tape-guide-member support for a cassette as defined in the first paragraph, which support is of a substantially elongate and blade-spring-like construction and comprises a central portion and two side portions which are situated adjacent the central portion and which are adapted to cooperate with abutment parts of a cassette, which support carries two tape-guide elements adapted to guide a magnetic tape.
A cassette of the type defined in the first paragraph, a pressure-member support of the type defined in the second paragraph, and a tape-guide-member of the type defined in the third paragraph are known from EP 0,492,705 A1.
In the cassette known from EP 0,492,705 A1 and shown in FIG. 6 of EP 0,492,705 A1 each of the two side portions of the pressure-member support directly abuts against an abutment pan. The two side portions of the tape-guide-element support, however, abut against the two abutment parts via the two side portions of the pressure-member support. As a result of this, the two side portions of the tape-guide-element support exert a force on the two side portions of the pressure-member support, which is unfavourable because the forces exerted on the side portions of the pressure-member support by the side portions of the tape-guide-element support limit the movability of the pressure-member support and, consequently, of the pressure member carried by this pressure-member support, which has a considerable influence on the force exerted on an introduced magnetic head by the pressure member. As a result of this, said force exerted on an introduced magnetic head by the pressure member becomes increasingly dependent upon tolerances of the penetration depth of the magnetic head. Moreover, owing to the abutment of the tape-guide-element support against the pressure-member support with the inserted magnetic head, the effect occurs that the pressure applied to the magnetic head by the pressure member exhibits a comparatively large hysteresis, and it has been found that larger pressure forces occur in dependence upon the insertion path during insertion of a magnetic head into the cassette than during removal of a magnetic head from the cassette. Such a hysteresis of the pressure force is undesirable because in operation this leads to undefined force relationships which depend to a comparatively large extent on penetration depth tolerances.